Construction of bobbin case rotation restraining means



D 1711968 R. E-JOHNSO'N" v Y 4 6' CONSTRUCTION OF BOBBIN CASE ROTATION RESTRAINING MEANS Filed April 26, 1967 INVENTOR- Fig.l Ralph EJahnson WITNESS United States Patent CONSTRUCTION OF BOBBIN CASE ROTATION RESTRAINING MEANS Ralph E. Johnson, Boonton, N.J., assignor to The Singer Company, New York, N.Y., a corporation of New Jersey Filed Apr. 26, 1967, Ser. No. 633,850 5 Claims. (Cl. 112-484) ABSTRACT OF THE DISCLOSURE A sewing machine having means for holding the bobbin case stationary and preventing it from rotating with the loop taker or hook as the latter moves about its axis.

BACKGROUND OF THE INVENTION Field of the invention The present invention relates to sewing machines and more particularly to a novel and improved rotation restraining means for the bobbin case of a vertical axis rotating loop taker, which restraining means also serves to releasably secure the bobbin case in proper operative position in the loop taker.

Description of the prior art It is generally known in the art to provide a sewing machine with means for restraining the rotation of the bobbin case. However, the prior art structures used to accomplish this result have, for the most part, had to add parts to the basic sewing machine structure for mounting the restraining means. The use of these additional parts significantly increases the overall cost and complexity of the machine. This increased cost is partly due to the greater number of machining operations required, the increased number of strict tolerances that must be main tained for the added parts, and the added costs of assembling a relatively greater number of parts. It follows that, as a result of the increased number of parts, the means for restraining the thread carrier becomes a relatively more complex structure thereby presenting the increased probability of failure of the parts which go to make up the structure, thus making the mechanism less dependable. Also, as is well recognized in the sewing machine art, the possibility of thread entanglement increases with a corresponding increase in the number of parts required to carry out the sewing operation.

SUMMARY OF THE INVENTION The present invention overcomes both these and other prior art deficiencies by providing a bobbin case restraining means located substantially entirely within the confines of the rotary hook and being secured in operative position by a pin used for mounting a throat plate which forms part of the basic structure of a sewing machine. The restraining means also includes a lug integrally formed with a nonrotatably mounted bracket and adapted to seat in a notch for-med in the bobbin case. The elevation of the lug is determined by the same elevation which determines the elevation of the bobbin case, which latter elevation as is well recognized in the art, is of a particularly critical nature in order to insure proper coaction of the rotary loop taker and the reciprocating needle thereby necessitating relatively strict tolerances. Thus by relying upon structure already present in the sewing machine, it is seen that the present invention substantially decreases the number of machining operations required in the manufacture of the sewing machine and consequently the number of required strict tolerances.

Accordingly, it is a primary object of this invention to provide in a sewing machine a novel and improved restraining means that is of relatively simple design, highly economical, durable, dependable and efficient, and that will stationarily maintain the bobbin case during operation of the sewing machine.

Another object of this invention is to provide in a sewing machine having a vertical axis rotating hook, a novel and improved bobbin case restraining means which requires a minimum number of components for the mounting thereof on the sewing machine bed.

It is a further object of the present invention to provide a novel and improved bobbin case restraining means which is accurately mounted on an existing structure in the sewing machine, whereby no additional machining operations on the sewing machine bed are required.

It is also an object of the present invention to provide a properly orientated bobbin case retainer having substantially all of its associated structure outside of the confines of the rotary hook thereby reducing the possibility of interference with rotation of the hook as well as thread entanglement.

Having in mind the above and other objects that will be evident from an understanding of this disclosure, the invention comprises the devices, combinations and arrangements of parts as illustrated in the presently preferred embodiment of the invention which is hereinafter set forth in such detail as to enable those skilled in the art readily to understand the function, operation, con struction and advantages of it when read in conjunction with the accompanying drawings in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the bobbin case restraining means in accordance with the invention,

FIG. 2 is a top plan view of the bobbin case, the rotation restraining means and the loop taker of the sewing machine,

FIG. 3 is a vertical sectional view taken substantially on the line 33 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention is illustrated as embodied in a sewing machine construction substantially in accordance with the sewing machine that forms the subject matter of the United States Patent of Johnson, No. 3,051,107, Aug. 28, 1962, wherein the machine is fully disclosed and to which reference may be had for a more complete understanding thereof.

With reference to the drawings, there is illustrated frag mentary portions of a bed 1 of a frame of a sewing machine having a laterally disposed U-shaped ledge 2 which is integrally formed with the inner surface 3 of a side wall of the bed 1, and which is adapted to provide a seat for a throat plate 4 and a slide plate 4 upon which throat plate the work is to be supported and held down by a presscr foot (not shown). The throat plate 4 is adapted to be secured in its operative position by the combined coaction of a conventional spring loaded clamp generally indicated at 5, having a head 6, and a mounting stud or position pin 7 located transversely of the clamp 5 adjacent to the side wall of the bed 1. The position pin 7 must be accurately located so that the throat plate can be properly held in place on the ledge 2. The clamp 5 is disposed in a boss 8 integrally formed with both the inner surface 3 and the ledge 2, while the position pin 7 is mounted in a recess formed in a bracket supporting shelf 9', the latter of which is integrally formed with and transversely disposed from the surface 3. The throat plate and slide plate provide a top cover for the sewing mechanism situated within the bed 1, while a platform 10 of the bed 1 forms a support upon which the said mechanism may be mounted.

As best illustrated in FIG. 3, an integrally formed depending hook shaft 11 of a vertical axis circularly moving loop taker of the rotating hook type, indicated generally at 12, is journaled in the platform 10. Rotation is imparted to the hook shaft 11 by an actuating mechanism similar to that described in the aforementioned Johnson patent. The rotary hook 12 is generally cup-shaped and comprises an outer ring 13 and the hook shaft 11 which is journaled in a bore 14 of a bushing 17 disposed in the platform of the bed 1. A boss 15 having an exposed peripheral surface 16 (see FIG. 1) is formed with a recess and is adapted to receve the hook shaft and bushing therein. The bushing 17 is concentrically located relative to the shaft 11 and comprises a concentric flange 18 seated on the milled surface 16 of the boss 15. The vertical orientation of the hook is established with reference to the platform 10 and must be maintained within a relatively strict tolerance as is also true of the lateral orientation of the hook, for proper coaction with a reciprocating needle 23 shown in FIG. 3. The bore 14 is connected to the outer ring 13 of the rotary hook 12 by way of an arm 14 which efiectively defines the bottom of the ring. The bottom of the ring is open except for the said arm. The ring 13 is also open at the top and has an inwardly directed flange 19 terminating in a free edge 20 which is circular and disposed concentrically of the axis of the hook shaft 11. The continuity of the flange 19 is broken only by a slot 21 cut through the flange 19 from the free edge 20 and into the ring 13. The slot 21 is orientated to define a loop seizing beak 22 situated internally of the hook 12. It can be seen in FIG. 2, that except for a lug 47 and a portion of a spring-carrying member 58, both of which are to be discussed hereafter, a bobbin case rotation restraining means 40 is disposed entirely outside the confines of the rotary hook 12 so that it will not interfere with rotation of the hook or cause any unnecessary thread entanglement.

The needle 23 passes through a needle hole 24 formed in the throat plate 4. This hole must be accurately located for the needle to rise and dip without any sticking or rubbing which would interfere with good loop formation. This also requires that the opening in the bottom of the hook be located below the needle when it reaches its lowermost position (see FIG. 2) so that the needle can form the thread loop. Thus the importance of properly locating the throat plate and the hook is readily apparent, the former being accomplished by way of pin 7 and the latter by boss 15. Included among the functions of the needle 23 is that it carries thread (not shown) through the needle hole 24 below the throat plate 4 where the stitch forming mechanism, to wit, the loop taker or hook 12, can enter a thread loop formed by the needle at the proper time thereby forming the desired stitch. Thus, it is apparent that the loop seizing beak 22 must be at the proper elevation for the beak to seize the loop formed when the needle carries the thread down through the needle hole 24. This is best illustrated by the relative location of the needle 23 and loop seizing beak 22 shown in FIG. 3. An inaccurate elevation of the hook can produce a faulty stitch because the beak of the hook will not properly enter the thread loop formed by the needle.

A thread carrier or more specifically a bobbin case, generally indicated at 25 (see FIG. 2), is eccentrically situated Within the periphery of the rotary hook 12 relative to the axis of the hook shaft 11. The bobbin case is mounted, as discussed below, so that the ring 13 can rotate relatively thereto. The bobbin case 25 includes a recess defined by an annular wall 26 (FIG. 3) for receiving a thread carrying bobbin 27. The bobbin seats on a flange (not shown) extending inwardly from the lower portion of the wall 26 towards the center of the recess. The bobbin case is provided with a finger notch 28 which facili tates removal of the bobbin. Extending endwise from approximately the mid-point of the wall 20 is a transversely disposed flange 29. In order to support the bobbin case in the ring 13 of the rotary hook 12 there are provided cooperating bearing surfaces between them. Towards this end, there is provided on the bobbin case 25, as shown in FIG. 3, a peripheral groove 30 comprising a lower surface 32 and a peripheral bearing surface 33 which is adapted to receive the inner flange 19 of the ring 13. As illustrated in FIG. 3, an upper surface 31 of the groove 30 bears against the top surface of the flange 19, the lower surface 32 bears against the bottom surface of the flange 19 and the peripheral surface 33 is formed so as to be complemental to the free edge 20 of the flange 19, which edge normally abuts against the surface 33. As illustrated in FIG. 2, the flange 29 has a notch 34 formed therein adapted for receiving a lug and comprising a finger 35, a shoulder 36 and an abutment face 37. At its end opposite from the notch 34 the flange 29 has an abutment surface 33 which, during normal operation of the sewing machine, bears against a rotation restraining spring member. For a more specific description of the remaining structural parts of the bobbin case reference may be had to aforementioned Johnson patent.

The bobbin case 25 is generally semicircular in shape with a diametrical edge 39 defined by the abutment surface 38, an adjacent edge of the wall 26, and an edge of the finger 35. Thus, as best illustrated in FIG. 2, when in operative position the bobbin case 25 is disposed eccentrically within the ring 13 with the peripheral bearing surface 33 against the free edge 20 and the diametrical edge 39 disposed substantially diametrically of the ring 13. In order to maintain the above described operative position of the bobbin case 25 and to prevent it from rotating as the hook 12 turns, there is provided a bobbin case retainer generally indicated at 40.

As shown in FIG. 1, the retainer 40 includes a positioning bracket 41 having a U-shaped flange 42 mounted on a threaded stud 43. The stud 43 is in a hole 44 formed in the platform 10 provided for the mounting of the rotary hook 12 and is secured to the platform by a nut 45 on the threaded stud 43 at the underside of the said platform 10. The hole in which the stud 43 is mounted is defined by a boss 46 on the upper surface of the platform 10. The surface of the boss 46 provides a seating surface for the lower surface of the U-shaped flange 42, as shown in FIG. 3, and is at substantially the same elevation relative to the upper surface of the platform 10 as is the surface 16 of the boss 15 which receives the hook shaft 11 and the hook shaft bushing 17. Thus, by having the surfaces of the bosses 15 and 46 at identical elevations relative to a common reference surface, to wit, the upper surface of the platform 10, only a single milling operation is required to establish them at the desired distance from the said reference surface. The flange 18 of the bushing 17 is of such depth as to properly elevate the rotary hook 12 when considered in conjunction with the height of the boss 15 relative to the upper platform surface for proper operative relationship with the reciprocating needle and the throat plate. The bobbin case retainer 40 includes a conventional lug 47 having a substantially chisel-shaped cross-section, a flat inclined abutment surface 48 and a transversely disposed substantially flat surface adjacent thereto. The lug 47 functions to secure the bobbin case against roation by seating in the restraining notch 34 thereof so that the inclined abutment surface 48 bears against the abutment face 37 of the notch 34 as the bobbin case 25 tends to rotate in a clockwise direction caused by the rotation of the ring 13 about its axis. The lug 47 is mounted on and adjacent the free end of a supporting finger 50 which is disposed inwardly of the periphery of the ring 13. The lug 47 is arranged relative to the surface of the boss 46 so that it substantially corresponds to the elevation of the restraining notch 34 of the bobbin case 25 as determined by the height of the ring 13 with which the bobbin case 25 is operatively associated, whereby the reference surface of the platform is relied upon as the common base for all these elevations. Thus it is seen that the elevation of both the lug 47 and the bobbin case 25 is critical and must be maintained within strict tolerances during manufacture of the structural components which give the parts their overall height in order to produce a properly operative sewing machine. Failure to locate the lug and bobbin case at substantially the same elevation would result in the lug not properly seating within the notch 34 and thus, accordingly, there would not be any restraining force to preclude undesirable clockwise rotational tendency of the bobbin case. The lug 47 is laterally spaced at such a distance from a triangularshaped vertical wall 51 integrally formed with the flange 42 to allow for the ring 13 of the rotary hook to freely pass therethrough. The supporting finger 50 upon which the lug 47 is mounted, is joined by a top wall 52 and a wall transversely depending therefrom. The radial location of the lug 47 is accomplished by means of properly locating the parts comprising a retainer 40 and particularly, by way of a fork-shaped finger 53 adjacent the top Wall 52 of the positioning bracket 41 whose prongs or tines 5455 are substantially circumferentially disposed relative to the position pin 7 used to position the throat plate of the sewing machine. The location of this pin is highly critical and requires strictly maintained tolerances in order to properly locate the throat plate. The pin 7, as best illustrated in FIG. 1, is mounted on the shelf 9 integrally formed with and transversely extending from the lower part of the side wall of the ledge 2. The bobbin case retainer 40 further includes a releasably mounted pivotal member 56 which pivots about the axis of a screw 57 fastening the member 56 to the top wall 52 of the positioning bracket 41, a spring-carrying member 58 secured to the pivotal member 56 between the extremities thereof by means of screws 59, and a substantially L-shaped supporting member 60 mounted on the shelf 9 with a pair of screws 61. The pivotal member 56 is elongated and has an upwardly inclined lip portion 62 depending therefrom and is adapted to be manually lifted up and urged away from or towards the abutment surface 38 of the bobbin case 25, as the case may be. The spring-carrying member 58 comprises a top surface 63 having a portion 64 extending beyond an edge of the pivotal member 56 wherefrom depends a bias portion 65 which is adapted to limit any counterclockwise rotational tendency of the bobbin case 25 by means of a downwardly bent arm 66 terminating in a spring section 67 constructed and arranged so that it will bear against the abutment surface 38 of the bobbin case. The bias portion 65 has a certain amount of resiliency inherently present therein and accordingly requires some restriction on its counterclockwise movement. This end is accomplished by means of a limiting flange 68 spaced from the lip 62 and having angularly orientated surfaces adjacent one another. The lowermost portion of the limiting flange 68 is spaced from and disposed rearwardly of the spring section 67 relative to the abutment surface 38 of the bobbin case 25. This latter portion will bear against the rear surface of the spring section 67, should the section be urged backwards, thereby limiting the sections lateral displacement.

The bobbin case retainer 40 is provided withan arrangement at the free end of the pivotal member 56 which positions the said member and thus the spring section 67 fastened thereto whereby there is provided a means for adjusting the restraining tension with which the bobbin case 25 is secured in operating position. The arrangement includes a cup-shaped washer 69 having a central aperture and a peripherally disposed rim 70. The washer 69 is received within an elongated opening 71 in the pivotal member 56 and is secured to the supporting member 60 by a screw 72. The central aperture of the washer 69 is substantially greater than the shank of the screw 72, to provide for adjustment of the washer in a radial direction of the pivot screw 57 and hence, for adjustment of the alignment of the spring section 67 relative to the abutment surface 38 of the bobbin case 25. The head of the screw 72 is disposed entirely within the periphery of the washer 69 and has a surface which is in substantially the same plane as the upper surface of the rim 70 thereby precluding the possibility of any thread becoming entangled with the screw head. The pivotal member 56 is adapted to be lifted from its normal operative position around the washer 69 and swung about the pivot screw 57 allowing for movement of the free end of the said pivotal member away from the bobbin case 25 thereby permitting ready removal of the bobbin case 25 from the ring 13.

Numerous alterations of the structure herein disclosed will suggest themselves to those skilled in the art. However, it is to be understood that the present disclosure relates to a preferred embodiment of my invention which is for purpose of illustration only and not to be construed as a limitation of the invention. All such modifications which do not depart from the spirit of the invention are intended to be included within the scope of the appended claims.

Having thus set forth the nature of this invention, What I claim herein is:

1. In a sewing machine having a frame, a bed forming a lower portion of said frame, said frame having a head portion, said head portion having an end'wise reciprocatory thread-carrying needle disposed therein, said bed having a positioning pin supported therein, said bed including a platform for supporting a lower stitch-forming mechanism, said platform being provided with a first raised portion and a second raised portion, a circularly movable loop taker journaled in said platform and including a ring, said loop taker being seated on said first raised portion of said platform and being elevated relative thereto whereby said loop taker operatively coacts with said thread-carrying needle, a bobbin case, said bobbin case and said ring having cooperating bearing surfaces arranged so that said bobbin case is also elevated relative to said platform, said ring supporting said bobbin case while allowing for circular movement of said ring relative to said bobbin case, constraining means for preventing said bobbin case from movement with said ring or relative thereto, said constraining means being constructed and arranged so that said bobbin case is releasably restrained from circular movement, said constraining means cooperating with said positioning pin to properly locate said bobbin case relative to said needle, said constraining means being seated on said second raised portion of said platform and being elevated relative to the same surface as the bobbin case and the rotary hook, said first and second raised portions of said platform having substantially the same elevation relative to said platform, whereby said platform provides a common reference surface.

2. In a sewing machine in accordance with claim 1 wherein said constraining means is constructed and arranged so that it is located'substantially entirely outside the peripheral confines of said loop taker, said constraining means having only the circular restraining portion thereof being operatively associated with said bobbin case whereby said constraining means does not interfere with movement of said loop taker.

3. In a sewing machine in accordance with claim 1 wherein said bobbin case includes a restraining notch adapted for receiving a lug therein, said constraining means comprising a positioning bracket including a lug thereon, said lug being orientated so that it operatively engages said notch to preclude circular movement of said bobbin case.

4. In a sewing machine in accordance with claim 3 wherein said constraining means further includes a bias portion for operatively engaging a surface of said bobbin case whereby said lug prevents circular movement of said bobbin case in a first direction and said bias portion limits circular movement of said bobbin case in a direction opposite said first direction.

5. In a sewing machine having a frame including a work supporting bed and an overhanging bracket-arm terminating in a head, an endwise reciprocatory needle bar journaled in said head, a thread carrying needle fixed in said needle bar, a circularly movable loop taker supported in said work supporting bed and disposed to cooperate With said thread carrying needle in the formation of lock stitches, a throat plate mounted on said work supporting bed and provided with a needle hole through which said needle reciprocates, a stud fixed in said work supporting bed and disposed to assist in holding said throat plate in correct register with said endwise reciprocating needle, a platform formed in said bed and providing a bearing supporting said loop taker for circular movement, a bobbin case journaled in said loop taker, and bobbin case rotation restraining means cooperating with said bobbin case to restrain said bobbin case from moving References Cited UNITED STATES PATENTS 1,149,049 8/1915 Hemleb 112228 X 1,996,290 4/1935 Gunther 112228 X 2,966,130 12/1960 Johnson 1l2-184 3,173,390 3/1965 Bartose 112-184 X HERBERT F. ROSS, Primary Examiner.

US. Cl. X.R. 112228 

